One-Dimensional Magneto-Optical Nanostructures: Template Synthesis, Structure, Properties, and Application in Spectroscopy Based on Plasmon Resonance

A method for the formation of magneto-optical one-dimensional (1-D) nanostructures by the electrodeposition method into the pores of track-etched membranes is presented in this letter. Two possible techniques are considered: the synthesis of magnetic nanotubes and their subsequent coating with silver, as well as the synthesis of vertical-standing arrays of layered magneto-optical nanowires (NWs) with alternating layers of nickel and silver. The resulting nanotubes and NWs are polycrystalline microstructures with a nanostructured plasmon-active surface. The absorption spectra have a distinct peak corresponding to the position of the local plasmon resonance: in the near-infrared range for the nickel nanotubes coated with silver and in the optical range for the layered NWs. For layered NWs, there is a combination of absorption peaks of both silver and nickel. The use of the obtained 1-D magneto-optical nanostructures for the formation of plasmon-active magnetically controlled substrates as surface-enhanced Raman spectroscopy (SERS) active surfaces is suggested for the detection of Rhodamine 6G in concentration down to 10–9 M. The increase of SERS signal intensity by using a magnetic field is shown for concentration 10−3 M with an extra signal amplification of more than four times.